A confined laser cutting tool utilizing a focused laser beam may be used for precise cutting or drilling on a workpiece, such as to create cooling passages through an airfoil of a turbomachine. A confined laser cutting tool includes a laser, a focusing lens, a water chamber and a nozzle. The laser passes through the focusing lens and then into the water chamber, usually via a window in the water chamber. The water chamber also includes a nozzle on the side of the water chamber facing the workpiece. The nozzle forms a water jet directed to the work piece. The focusing lens focuses the laser such that the laser passes through the water chamber and into the water jet emanating from the nozzle. The laser beam is confined within the water jet due to total internal reflection at the air-water boundary, that is, the laser beam is completely reflected at the air-water interface and thereby may be focused and guided to the workpiece. In order to achieve total internal reflection, the beam must approach the boundary at certain angles, i.e., above a particular critical angle. The jet of water also must be highly stable with consistent boundaries to prevent the laser beam from escaping. The shape and dimensions of the nozzle help to ensure proper interaction of air and water to maintain the confined laser.
Nozzles for use in such confined laser cutting tools are typically made of materials with very high hardness, such as sapphire or diamond. However, even nozzles of such material may eventually be consumed or depleted. If the nozzle of the confined laser cutting tool becomes damaged or worn, the water jet may become unstable which can reduce the ability of the water jet to focus and confine the laser, resulting in diminished energy delivered from the laser to the workpiece which impairs the function of the confined laser cutting tool.